When it comes to CB radios, it's all about going the distance."They all want to get out as far as they can," says Jamie Trenholm of Durham Radio Sales, referring to customers at the Whitby, Ont store....
When it comes to CB radios, it’s all about going the distance.
“They all want to get out as far as they can,” says Jamie Trenholm of Durham Radio Sales, referring to customers at the Whitby, Ont store. They may not want to talk to Mexican truckers, but a clear connection to trucks that are traveling the same stretch of highway doesn’t seem like an unreasonable request.
But just how do you ensure that distance and a clear signal, 10-4? When they come out of the box, CBs all pump out the same 40 channels and a maximum legal limit of four watts. (We won’t talk about the illegal use of linear amplifiers or power boosters).
The good news is that you don’t have to empty your wallet for effective CB reception. An entry-level CB and a good antenna will reach as far as pricier models with small antennas, says Ramone Sandoval, the product manager for CB radios at Cobra Electronics. “But you won’t have the extra performance enhancing – or professional – controls.” For that you need to consider higher-priced systems.
What you can be guaranteed on an entry-level system is a squelch control that ensures you aren’t listening to static all day, the volume control and the power switch.
In general, the performance of a CB generally comes down to a balance of antennas and the weather. A clear night sky and a position on a hill will offer the best distance, but there’s only so much you can do to guarantee that. If it’s a sunny day (particularly in the recent days of heavy sun spot activity) you’re going to face interference. So that leaves you with the antennas.
When it comes to CB reception, a bigger truck is going to perform best. After all, it’s the second part of the antenna, says Michelle Coghill, manager of Wilson and Francis Antenna. “And a lot of the newer (aerodynamic) trucks have lower mirrors, kind of recessed, and you can’t get over the roof line without a real long-shafted antenna.”
It’s obvious why the mirrors are a good choice for mounting positions. They’re mounted away from the truck, and make for an easy reach above the roof line. A top-loaded antenna will have to have two thirds of its length above the roof, while a centre-loaded model should have its coil mounted just above the roof line. (Base load antennas are only practical for pick-ups.) For car haulers, the most likely mounting location is on the headache rack behind the cab.
“The ideal antenna for a CB is a nine-foot antenna, but it’s impractical,” Sandoval says. “Engineers have made these antennas shorter. They have a load built into it that compensates for the missing height.”
But mounting considerations aren’t limited to height. If you tilt the antennas forward for a “bullhorning” look, you are also changing the angle of the antenna’s radiation, and that can affect performance. If you need to tilt an antenna for the sake of height restrictions, try to keep the range between 10 to 15 degrees.
“Some guys run two of them, but that doesn’t mean double the distance,” Trenholm adds. At best, you’ll improve performance by 25 to 30 per cent, Coghill agrees.
Once the antennas are mounted, it’s then a matter of matching them.
ABCs of SWR
Matching is made possible with the needle of an SWR (standing wave ratio) meter, which is available on any serious CB. You’re shooting for a ratio of 1.5:1, but anything higher than 2.5 or 3.0 is particularly unacceptable.
“Spending more time trying to get all three to 1.5 isn’t worth it. But a lot of guys, they want to get it down below,” Coghill says.
Once you’re at the level of checking the SWR, take separate readings on Channel 1, 20 and 40. If it’s higher on 40 than 1, you have to raise the antenna. If it’s raised as high as it will go, you may simply need to buy a longer whip. If it’s lower, that means you have to drop the antenna. In the worst case scenario, that may mean cutting the whip.
For at least one element of the installation of a CB, neatness doesn’t count. Typically, you’re stretching 18 feet of coaxial cable between the antenna and the radio. But any extra cable should be stuffed underneath the dash or under a carpet, and not rolled into a neat coil. Coils like that can create what’s known as an RF choke that will de-tune the antenna. The end result will be an SWR that won’t drop below 2.0:1.
If your SWR reads 3.0:1 on all channels, the antenna likely isn’t grounded. And part of the problem may be linked to the truck that you bought. Fiberglass cabs or air-ride suspensions can act as insulation between the mirror and the chassis or the frame’s ground. If you’re dealing with either case, you’ll need to run a jumper wire to the frame, linking pieces of wire that are no more than four feet long to the door hinges, and then from the door hinges to the frame.
A ground between the chassis and the radio – in addition to the power ground – is another good bet. Simply loosen a screw on the back or side of the radio’s casing and connect a wire to this point.
Keep in mind that an improperly balanced antenna can actually damage the radio. They’ll handle a 6:1 mismatch; anything higher can cause radio components to wear out.
If your signal breaks up when the truck is moving, but is clear when you’re stopped, you’re probably facing a problem with the connections. Check the coax and the antenna itself. But if the signal problem occurs all of the time, there’s probably a problem with the unit itself.
Once the antenna is in place, the radio itself begins to play its role.
The first step is to adjust your squelch control. The squelch control acts like a gate for the receiver, Sandoval says. “But then you are sacrificing the low-level signals that don’t break through.”
Higher-end CBs come with noise reduction systems that work much like the Dolby function on a stereo, Sandoval says (such systems are known as Sound Tracker on the Cobra line). “It suppresses some of the noise associated with CB signals.”
Many of those can come from the operation of the truck itself.
RF and mic gain
The RF signal is effected by such things as terrain (a building can block it), the time of day (nighttime is best) and the efficiency of your antenna.
In most cases, you want to leave the RF gain on full, to amplify the signal as much as legally possible. “The only time you would back off is if the signal was extremely strong and you were getting distortion,” says Steve Bekker of Toronto-based Radioworld. But the setting for the mic gain will depend on your own voice. If you’re soft-spoken, you’ll want a higher setting.
If you’re facing static that disappears when you travel down a wet highway, you can probably blame a static charge from radial tires. When you drive on the wet pavement, the static will discharge. But since you can’t control the weather, you can also solve the problem by hanging a drop chain from the rear axle, or purchase a special rubber strap that’s impregnated with metal. As the metal from these add-ons touches the pavement, the static charge is sent into the ground rather than over your CB speakers.
Heated mirrors can also interfere with an antenna’s tuning. But if it really bothers you, the fuse for the mirror can be removed, or you can install a switch to offer a heating element when you need it, and switch off the power when it’s simply annoying.
But also be ready to accept that there are some issues out of your control. “Right now, there’s a lot of sun spot activity which drastically affects communications,” Sandoval says. “We’re at a peak (of activity) right now and it will last for the rest of the year. But there might be a day where it could be overcast, and you might be able to get five miles. ” n